On Thursday, May 17, 2012 at 1:53:14 PM UTC-4, mike wrote:
I want to look at the eclipse this weekend.
Everybody says a #14 welding shade is good.
I don't have one.

So, how do the numbers stack up when you use 2?
I'm guessing it's not linear, so 7+7 doesn't = 14???

What's the math for stacking welding shades?

Thanks, mike

you can not stack the lens, can still have severe damage, this is coming directly from NASA.